This invention generally relates to a method and apparatus for measuring a thickness of a coating on a part by using a laser.
In the manufacture, repair or replacement of a part, the part may require the application of a coating. For high precision components, such as aircraft parts, the thickness of the coating may affect whether a part is in conformance with specification. Accordingly, the part is typically measured following complete application of the coating to make this determination.
In the past, gauges, such as micrometers, were used to measure the overall dimension of the coated part. This technique may not be accurate due to gauge error, user error or variation in the technique of using the measuring instrument. Furthermore, because the part is often measured after a coating application, the part may have too much or too little coating applied.
In addition, thermal spraying of a coating, such as by plasma or HVOF spray, may significantly heat the part. Due to thermal expansion, the part may not be accurately measured. For example, the part may be measured at a high temperature when it is expanded compared to measuring the part at room temperature when it is smaller.
A need exists for a more accurate technique and apparatus for measuring a coating on an object, such as a part.